The alpha5(IV) and alpha6(IV) chains of basement membrane type IV collagen are encoded by the genes COL4A5 and COL4A6, which are situated head-to- head on the X chromosome and divergently transcribed. Mutations in COL4A5 give rise to Alport syndrome (AS), an inherited disorder of glomerular basement membrane causing progressive renal insufficiency, often in association with hearing loss and ocular abnormalities. Deletions spanning the 5' termini of COL4A5 and COL4A6 have been identified in cases of AS-diffuse leiomyomatosis, in which AS is accompanied by disseminated smooth muscle tumors. The overall objective of this project is to elucidate the transcriptional regulation of COL4A5 and COL4A6. Specific aims are to map precisely and characterize the putative bidirectional promoter for these genes, and to define cis- and trans-acting regulatory elements which account for tissue- specific patterns of expression. The work will be performed in the outstanding environment of Harvard Medical School in the laboratories of Dr. Jing Zhou, an expert on the molecular genetics of basement membrane collagens, and Dr. William W. Chin, an expert on mammalian gene regulation. Consultants include Dr. Bjorn R. Olsen, an authority on collagens and extracellular matrix; Dr. Yoshihiko Yamada, an expert on the transcriptional regulation of type IV collagen genes; and Dr. Lawrence F. Brown, who has extensive experience with in situ hybridization. Methodologies to be used include RNase protection assays and primer extension analysis for identification of transcription start sites; transient transfections with reporter gene constructs for localization of promoter and cis-acting regulatory elements; development of transgenic mice to study tissue-specific gene expression; characterization of DNA-binding elements; and in situ hybridization. The applicant is a graduate of the Medical Scientist Training Program at Washington University, who has a record of accomplishment in the area of epithelial ion channels. He is committed to a basic scientific career in an academic division of nephrology. The proposed project will be carried out in a superb training environment with the strong support of experienced researchers. It will pose a series of strategic challenges which will provide excellent background for launching an independent career.